Family:Accipitridae, Genus Haliaeetus, Species
leucocephalus
The Accipitridae family,, which also includes hawks, kites, and old-world
vultures. Scientists loosely divide eagles into four groups based on their
physical characteristics and behavior. The bald eagle is a sea or fish eagle.

Subspecies: There are two subspecies of bald eagles. The
"southern" bald eagle, H. l. leucocephalus, is found in the
gulf states from Texas and Baja California across to South Carolina and Florida,
south of 40 degrees north latitude. The "northern" bald eagle, H.
l. alascanus, is found north of 40 degrees north latitude across the entire
continent. The largest number of northern bald eagles are in the Northwest,
especially in Alaska. The "northern" bald eagle is slightly larger
than the "southern" bald eagle. The two subspecies integrate with one
another in the central and northern states.

Size: The female bald eagle is 35 to 37 inches, slightly larger than the
male. The wingspan of a female ranges from 79 to 90 inches. The male bald eagle has
a body length from 30 to 34 inches. The wingspan of a male ranges from 72 to 85 inches.
Mature bald eagles weigh from ten to fourteen pounds. Females are about 30%
larger than males. Northern birds are
significantly larger than their southern relatives.

Color: The white head and tail and the large dark brown body and wings
are the features that distinguish adult bald eagles from other raptors. The
adults also have yellow eyes, cere (base of beak, including nostrils), bill,
legs, and feet with black claws. There are at least five different plumages that
apparently correspond with age; Juvenile, Basic I, Basic II, Basic III, and
Adult. Juvenile bald eagles are a mixture of brown and white; with a black bill
in young birds. The distinctive adult plumage develops when they're sexually
mature, at about 4 or 5 years of age.

Life expectancy: Wild bald eagles may live as long as thirty years,
but the average lifespan is probably about fifteen to twenty years. Eagles sit
at the top of the food chain, making them more vulnerable to toxic chemicals in
the environment, since each link in the food chain tends to concentrate
chemicals from the lower link.

Diet: Bald eagles feed primarily on fish, but will hunt other animals
like small mammals, waterfowl, snakes and carrion. Nearly all the fish that eagles
catch are either dead or in shock due to winter temperatures. Eagles will
consume approximately 1 to 2 pounds a day.

Tolerance to cold temperatures: A bald eagle's skin is protected by
feathers lined with down. The feet are cold resistance because they are mostly
tendon. The outside of the bill is mostly nonliving material, with little blood
supply.

Amy Reichardt of the World Bird Sanctuary in
St. Louis County
helps a young visitor build a model life sized bald eagle nest

Fidelity and nesting: Once paired, bald eagles remain together for
life. If one dies, the
survivor will not hesitate to accept a new mate. Bald eagles build some of the
biggest nests in the world averaging 7 feet across and 5 feet deep. The eagles
return to the same nest annually with improvements made each season. The female
will lay 1 to 3 chicken sized white eggs in the spring. The eggs will hatch
after about 35 days and both parents take on parental duties until the young are
about 12 weeks old when they are old enough and strong enough to fly on their
own.

Voice: Shrill, high pitched, and twittering are common descriptions
used for bald eagle vocalizations. Eagles do not have vocal cords. Sound is
produced in the syrinx, a bony chamber located where the trachea divides to go
to the lungs. Bald eagle calls may be a way of reinforcing the bond between the
male and female, and to warn other eagles and predators that an area is
defended.

Skeleton: An eagle's skeleton weighs about half a pound (250 to 300 grams), and is only
5 or 6 percent of its total weight. The feathers weigh twice that much. Eagle
bones are light, because they are hollow. The beak, talons, and feathers are
made of keratin.

The wings and soaring: An eagles wings are long and broad, making them
effective for soaring. To help reduce turbulence as air passes over the end of
the wing, the tips of the feathers at the end of the wings are tapered so that
when the eagle fully extends its wings, the tips are widely separated. To help
them soar, eagles use thermals, which are rising currents of warm air, and
updrafts generated by terrain, such as valley edges or mountain slopes. Soaring
is accomplished with very little wing-flapping, enabling them to conserve
energy. Long-distance migration flights are accomplished by climbing high in a
thermal updraft, then gliding downward to catch the next thermal updraft, where the process is
repeated.

Eagles can fly at speeds up to 65 miles per hour at level flight and reach
speeds of 150 miles an hour in a dive. The wings are not only equipped for
flight but can be used as paddles to swim to shore if a caught fish is to heavy
to carry.

The tail: The tail is very important for flight and maneuvering. While
the bald eagle is soaring or gliding in flight, the tail feathers are spread, in
order to attain the largest surface area and increase the effect of thermals and
updrafts. The tail also helps to brake the eagle when landing and assists in
stabilization during a controlled dive or swoop toward prey. The strength of the
feathers and the follicles holding the feathers is quite impressive, while
watching the tail move back and forth and up and down during maneuvers.

Feathers: Bald eagles have 7,000 feathers. Eagle feathers are
lightweight yet extremely strong, hollow yet highly flexible. They protect the
bird from the cold as well as the heat of the sun, by trapping layers of air. To
maintain its body temperature an eagle simply changes the position of its
feathers. While an eagle suns itself on a cold morning, it ruffles and rotates
its feathers so that the air pockets are either opened to the air or drawn
together to reduce the insulating effect. Feathers also provide waterproofing
and protection, and are crucial for flight. Feather structure makes pliability
possible. Overlapping feathers can form a dense covering, which the birds can
open or close at will. The bald eagle has several layers of feathers, each
serving a different function. Under the outer layer of feathers is an inner
layer of down or smaller feathers.

The inter locking of feathers is an astonishing design of nature. The
feathers enable eagles to live in extremely cold environments. Eagles do not
have to migrate to warmer areas each year to fulfill temperature requirements,
they migrate to available food supplies. A lone eagle feather is believed to
convey great power. North American Indians incorporated the eagle's primaries
and tail feathers into their ceremonies and legends.

The beak and talons: The hook at the tip of the beak is used for
tearing. Behind the hook, the upper mandible, the edge sharp enough to slice
tough skin, over laps the lower, creating a scissors effect. A bald eagle's beak
is a strong weapon, but is also delicate enough to groom a mate's feathers or
feed a small portion of food to a newly hatched chick. Talons are important
tools for hunting and defense. Eagles kill their prey by penetrating its flesh
with their talons. The talons are very strong and can grasp prey at strengths of
2600 pounds per square inch. This is the equivalent to driving a nail through
concrete. The beak and talons grow continuously, because they are made
of keratin, the same substance as our hair and fingernails. The beak of a
captive eagle is not worn down naturally, so must be trimmed annually.

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